Trench-digging machine



March 11, 1947. J. H. MacKlNNQN 2,417,313

TRENCH DIGGING MACHINE Filed June 17, 1944 2 Sheets-Sheet 1 March 11, 1947.

J. H. M KINNON 2,417,313 TRENCH DIGGING MACHINE Filed June 17, 1944 2 Sheets-Sheet 2 Patented Mar. 11 1947 UNITED STATES PATENT om'ce 2,417,313 TRENGH-DIGGING John H. MaKihnon, Larchi'noiit, N; Y. Application June 17, 1944, Serial No. 540,869

(01. ev n) Claims. 1 I

This invention relates to new and useful im provements in trench-cutting devices, and relates more particularly to a spiral cutting element adapted for cutting trenches through various soil formations, the device having means for cleaning the cut material, particularly roots, from the spiral cutting element as the same proceeds through the ground. The invention has particular reference to a combined trench-digging and cablelaying device wherein the spiral cutting element cuts a channel of approved depth in the ground,

means being provided for simultaneously laying the cable substantially at the bottom of the trench, without, however, actually removing more than a minimum quantity of the dirt from the trench as the machine proceeds.

The device of the present invention is adapted to be mounted on any suitable truck or tractor having sufiicient power to move the entire apparatus over the ground, as Well as to rotate the spiral cutting elements.

Spiral trench-digging assemblies wherein the spiral cutting element is forwardly inclined, and the cutting is done by the edges of the spiral element, have been known. They have-not been particularly satisfactory, however,.for a number of reasons, primarily because the spiral cutter soon becomes clogged with dirt, stones, roots, arid the like. The roots below the ground surface, as well as the vines, briars, and other growth above the ground, tend to wind themselves around the spiral cutting element, and it is frequently necessary to stop the operation of the machine and dig by hand around the spiral to remove the accumulated material. This greatly slows down operations, and somewhat better results appear to have been obtained, particularly in cable-lay ing operations, by simply pulling a large-sized plow through the ground, notwithstanding the enormous amount of motive power required for such an operation.

One particular difiiculty with the plow-type of cable-laying device resides in the fact that roots quickly gather along the forward edge of the plow and cause the same to rise to the surface of the ground. In this case, again, it is necessary to laboriously remove the roots and other accumulated material and start the operation all over again. In actual practice, it has usually been found necessary to first run the plow through the ground solely for the purpose of loosening the dirtand stones, and cutting the roots, and then proceed a second time through the same channel, this time, however, laying the cable at the bottom of the trench.

is an object of the present invention to provide a cable-laying device which may dig the trench and lay the cable in one operation. An important feature of the present invention resides in the provision of novel removable cutting teeth disposed about the periphery of the spiral conveying element.- These teeth are so formed as to out through any type of solidly-packed earth for mation, such as hard clay, shale, coral rock, and other sub-surface formations, as well as through roots which have always been a great source of annoyance. I I

Another important feature of the present invention resides in the provision of self-cleaning means for the spiral cutting element'such means comprising a second spiral element positioned 'just to the rear of the first spiral, the outer peripheral edges of the rear spiral being disposed inside of the cylinder formed by the outer periphery of the forward spiral cutter.

In another form of the present invention, the, two spiral elements are placed side by side rather than one behind the other, the two spiral elenients including the cutting teeth intermeshing as before, without, however, one element actually touching the other. This side-by-side arrangement produces somewhat faster cutting action, as will be pointed out more in detail hereinafter.

One of the spiral elements may be formed as a right-hand helix, and the other, as a left-hand helix, and in this instance the two spiral elements must, of necessity, revolve in opposite directions. In other words, the two spiral elements may be considered as intermeshing spiral gears whose teeth, however, never touch. Certain advantages, however, are achieved when both spiral elements are formed as a right hand helix, or as a lefthand helix, the two spiral elements, in this instance, revolving in the same direction. The advantages achieved by this arrangement will be pointed out more in detail. In either arrangement, the cutting edges or teeth of one cutting element are disposed quite near to the shaft forming the core of the other cutting element, and thus will remove all accumulated material as quickly as the same becomes imbedded or packed between the convolut-ions of the forward cutting element.

A further object of the present invention resides in the provision of novel supporting means for the cutting assembly wherein no journal support for the lower ends of the spiral cutting elements, or even of the cable chute, is necessary. This is an important feature of the present invention, particularly because any such lower journal support impedes the forward movement of 1 livered to the side of the trench.

In the drawings: Fig. 1 is a broken side elevation of a cablelaying device constructed in accordance with the present invenpresent invention, the view showing the cutting elements in operative position in full lines,'and

in inoperative position on the surface of the ground in broken lines.

Fig, 2 is a broken side elevation showing certain details of the pivotal supporting means for the upper end of the cutter assembly.

Fig. 3 is a broken side elevation of a modified form of cutter assembly wherein the forward spiral is formed with a right-hand helix, and the aft spiral with a left-hand helix, the View also showing. a shield in place of the cable-laying chute.

Fig. 4 is a section taken on line 4=5 of Fig. 3.

Fig. 5 is an enlarged section taken on line 5-5 of Fig. 1, the view showing certain details of the removable cutting teeth.

Fig. 6 shows a plurality of spirally-arranged cutting teeth.

Fig. 7 is an enlarged side elevation, partially in section, of the spiral element and two of the teeth secured thereto. I

Fig. 8 is an elevation of one of teeth.

Fig. 9 is an end view thereof.

Fig. 10 is a top plan view of a modified form of the invention wherein the twocutting elements are placed side by side rather than one behind the other.

Referring now more particularly to Figs, 1 and 2, it'will be noted that the cutter assembly includes a forward spiral element I0 and an aft spiral element II. The cutting teeth, illustrated more in detail in Figs. 5 to 9, inclusive, areillustrated only in fragmentary fashion in Fig. l, and for purposes of description the outer peripheral edges l2 of spiral l0, and the outer peripheral edges l3 of spiral Il, may be considered as the actual cutting edges. It may be pointed out in this connection that for digging trenches or laying cable through certain types of relatively soft soil formation known to be free from boulders and roots, the removable cutting teeth could be eliminated. Soil of this type, however, is relatively rare, and spiral elements fitted with the teeth hereinafter described will out faster through soilformation of any type, and accordingly are preferred. Only a. few teeth are shown on each spiral, and these only for the purpose of indicating that the cutting edges are disposed at M and I5, respectively, on spirals l6 and H.

the cutting Forward spiral Ill is carried on shaft l6, which is journalled in a pivoted frame assembly including lower journal element l8, and upper journal element l9. Aft spiral H is carried on shaft H, which is journalled at and 2i, such journal members being carried by frame member 22, which may be of channelled or I-beam construction, the pivoted frame assembly further including transverse frame members 23 and 24 which support journal members 18 and I9. It will be noted that spirals Hi and H are both formed as a right-hand helix, and,-accordingly, they should rotate in the same direction. The

- t3 and 42, respectively, connected by a chain 4 peripheral cutting edges I2 of forward spiral ID, at their rear, lie inside the cylinder formed by the peripheral edges E3 of helix H, and, likewise, such peripheral edgesv E3 of helix H, at their front, lie inside the cylinder formed by peripheral edges E2 of spiral w. The distance between cutting edges l3 and shaft l5 forming the core of spiral iii is a matter of choice, although it is pre:- ferred to have such edges positioned approximately an inch from the shaft. It is also of importance to have those portions of edges l3 lying nearest shaft If; to be spaced substantially equidistant between two convolutions of'the spiral.

The particular advantage in providing the two right-hand or left-hand spirals rotating in the same direction resides in the fact that the meeting edges of the two spirals are revolving in opposite directions, and accordingly any accumulated dirt, stones, roots, and the like, which are packed in the forward spiral are removed or cut away as they tend topass a center line defined by the axes of the two spirals. This prevents the accumulated material from being moved forwardly in the forward spiral.

Shafts l5 and IT carry sprockets 3B and 3| connected by a chain drive 32. The pivoted frame assembly further carries cable chute 34 which may be of rigid, tubular construction havig a rearwardly-disposed lower terminal, as shown at 35. Both of spirals l0 and H continue down to the lower end of shafts H5 and I1, and the lower end 35 of the cable chuteis positioned slightly above the lower terminals of such shafts; The pivoted frame assembly further includes a channel member 36, shown in Fig. 2, whichis freely.

pivoted on shaft 38 journalled in fixed frame assembly 39. I

At its upper end, shaft I6 is provided with a bevelled gear 31 which meshes with another bevelled gear (not shown) carried on transverse shaft 38. Fixed frame assembly 39 includes vertical frame members 40 which support shafts'38 and 4!, each of such shafts carrying sprockets drive as. Frame assembly 39 also includes vertical frame member 48 connected to frame member M1 by transverse members 49 Frame assembly 39 is appropriately bolted to vertical frame member 52,which is carried at the rear of the truck or tractor designated generally by the reference numeral 53. Suitable means (not shown) are provided for vertically adjusting frame assembly 39 relative to frame member 52, in order that when a somewhat deeper trench is to be dug, the frame assembly 32 may be dropped down wardly, and vice versa.

At the beginning of the cutting operation, the cutter assembly may occupy the position shown in bro-ken lines in Fig. 1, wherein the lower end of spiral element H] is positioned on top of the ground. Rotation of the cutters is then com menced, and the cutter assembly moves downwardly into the ground to the position shown in full lines in Fig. 1, having cut trench designated at 56. Brackets Gil, rigidly secured at the lower end. of frame members 52, may then be secured by bolts (5! to frame member 22, thus securely positioning the frame element for the spiral cutters at the. proper angle for cutting. This angle is a matter of choice, although'substantially -the angle illustrated in Fig. 1 has given the best .results. By lengthening bracket 60', howeventhis angle may be increased, which would be the case if a shallower trench is desired. Likewise, in the event that a deeper trench is being cut, a different bracket may be substitutedfor the bracket 60.

taken on line to the spiral conveyor anger Iii-the cutter assembly illustrated in Fig.- 3, the forward spiral It carried on shaft and journalled at I8 is similar to that shown in Fig. l. Aft spiral iii carried on shaft 7|, however, is a left-hand spiral, although its outer peripheral edges 12 are similarly disposed within the cylin der of spiral It, and the peripheral edges 12 of spiral it are positioned inside the cylinder of spiral Ill, as particularly illustrated in Fig. 4. In view of this right and left helix formation, it will be necessary to rotate both shafts i6 and 1| in opposite directions, which can be accomplished by securing intermeshing spur gears on shafts i6 and H, the spur gears being not shown.

In Figs. 3 and d, the cable chute 36 has been removed, and a curved shield iii has been substituted therefor, such shield being securely aihxed to frame member 22. This shield arrangement permits the dirt to be thrown upwardly and out of the ground, and if it is desired to deposit this dirt to the side of the trench, suitable conveyor means (not shown) may be employed. The width of the shield i5 is a matter of choice, and it will be appreciated that if th shield is as wide as the cut trench, all of the dirt will be removed. By providing a shield of lesser width, less of the dirt will be removed. For purposes of clarity, only a few teeth are shown on each of spirals HQ and H, such teeth having the cutting edges i? and i8, respectively.

The details of the cutting teeth are illustrated in Figs. 5 to 9, inclusive, Fig. 5 being a section 5-5 of Fig. 1. When the teeth are secured to the spiral in the manner hereinafter described, the spiral, per se, has no cutting func tion but rather is merely a conveyor for the out material, and for clarity hereinafter will be referred to as a spiral conveyor, although in the embodiment of Fig. 1 very little of the material is conveyed longitudinally of the spiral. Each cutting unit, designated generally by the reference numeral 85, may have a plurality of teeth 8i and 82 thereon. The individual units may be secured ill by means of bolts 83.

In the showing of Fig. 7 84 represents the upper surface of the spiral, the cutting units 82 thus being mounted on the lower surface 85 thereof. Since th upper surface 84 is the material-carrying surface, it is preferred to have bolt heads 86 counter-sunk. Each cutting unit may extend around the spiral 90; in other words, four of such units may be secured to each convolution of the spiral. The flange 8'? of each cutting unit is generally arcuate in shape, the opposed surfaces thereof conforming generally to the contour of a quarter of a convolution on the spiral element Hi. The teeth 82 extend from this flange portion, and the outer periphery 83 of each tooth represents the arc of a circle whose center passes through the axis of the rotating spiral. Each tooth is desirably formed on its forward edge with a hardened surface 89. By forming the teeth in this fashion, the major wear occurs on the outer periphery of each tooth, and especially on the leading edge thereof, which, as aforesaid, has a hardened facing. Accordingly, this wear only serves to reduce the width of the trench which is cut, and therefore the individual teeth may enjoy a relatively long life.

By referring to Fig. 9, it will be noted that the right-hand edge 9i of the lower tooth is in alignment with the left-hand edge 92 of the upper tooth. Also, the righthand edge 93 of the upper tooth is aligned with the left-hand edge of the first tooth on the cutting unit next adjacent.

Accordingly, it will be seen that the successive teeth on each revolution cut a complete channel. The flange of each cutting unit is further formed with a plurality of apertures 9t which receive bolts 83. By forming flange 81 so that each of its opposed surfaces has the contour of the marginal edge of the spiral conveying element, 'the cutting units may be reversed. In other words, either side may be secured to the spiral conveyor. It is not imperative that the cutting units be afnxed to the lower surface of the spiral conveyor, although experience has shown that best results are obtained when this arrangement is followed.

Both of the spiral elements, including the spiral conveyor and the cutting teeth, are illustrated in Figs. 1, 3 and l as being of substantially the same diameter. some cases the aft spiral cutting element may be somewhat smaller, since it has more of a cleaning function than a cutting function. In other instances, however, it may be desired to form the forward spiral cutter of smaller diameter in order to reduce the strain on this initial cutting element as it moves through the ground, the cutting element simply widening the trench as well as performing its usual cleaning function.

By including forward face 85 of the cutting teeth forwardly at approximately the angle shown, the cutting edges of the teeth are selfsharpening and do not tend to become rounded, as would be the case if this face were substantially parallel with the radius at the point of attachment to the spiral.

In the embodiment of the invention illustrated in Figs. 1 to 5, inclusive, one cutting element was placed to the rear of the first cutting ele ment, the forward cutting element primarily having the'function of cutting the trench, and the rear element, the function of cleaning the accumulated material from the forward element. In the showing of Fig. 10, however, the two cutting elements are placed side by side, and their axes are in transverse alignment. This arrangement includes shafts S6 and 97 carrying the spiral elements 98 and 99, respectively. The peripheral edges Hi0 and Hit of the respective spirals intermesh with each other, as shown, and the cutting teeth I @2 and is carried by each of the spiral elements approach the shafts 91 and 96, respectively. By revolving the cutting elements in the directions shown, the cut material is pushed rearwardly, each spiral element have accordingly botha cutting and a cleaning function. The cable chute I M may be positioned to the two cutting elements, or the shield similar to that shown in Fig. 4 may be employed.

This arrangement has the added advantage over that shown in Fig. l in that rotation of the two spirals side by side in the direction indicated very considerably aids in producin forward movement of the cutting apparatus through the soil. That is to say, in the arrangement shown in Fig. 1 wherein the forward cutter is moving in a clockwise direction, viewed from the top, that portion of the cutting element lying to the left of the center is moving in the same direction as the apparatus is moving, thus af fording on this side a considerable resistance to forward movement of the apparatus. That portion of the cutting element lying on the righthand side of the center, of course, moves in the direction opposite to that of the apparatus, thus partially offsetting the resistance afforded by the first-mentioned portion,

This is not necessary, however, and in and the teeth of' rear of the the pivotedframe structure In the arrangement of Fig. 10, however,- the major portion of the cutting action of both spirals is opposite to of the apparatus, and this movement Of the cutting teeth in the direction opposite to that of the apparatus actually aids very considerably in driving the apparatus forward. By placing the two spiral elements as close together as possible without having any actual engagement between the parts, this cumulative action is increased. This arrangement also produces effective cleaning action. 7

While several forms or embodiments of the invention have been shown and described herein for illustrative purposes, and the construction and arrangement incidental to several specific applications thereof have been disclosed and discussed in detail, it is to be understood that the invention is limimd neither to the mere details or relative arrangement of parts, nor to its specific embodiments shown herein, but that extensive deviations from the illustrated forms or embodiments of the invention may be made, without departing from the principles thereof.

What I claim is:

1. A trench-digging apparatus adapted to be mounted on a power-driven vehicle, said apparatus comprising a frame structure carried by the vehicle, a plurality of substantially parallel shafts journalled in said frame structure, one to the rear of the other, similarly-formed spiral conveyor elements carried by each shaft, means for rotating the spiral elements in the same direction, and cutting teeth carried adjacent the peripheries of each of said spiral conveyor elements, the cutting teethof each spiral element lying inside the cylinder formed by the cutting teeth of the other spiral element, the cutting teeth of the rear spiral element removing the accumulated material from the forward spiral element.

2. A trench-digging apparatus adapted to be carried on a power-driven vehicle and comprising a fixed frame structure mounted on the rear of the vehicle, and a pivoted frame structure carried by the fixed frame structure, means extending between the frame structures for securing at a desired inclination, a front and a rear spiral conveying element journalled in the pivoted frame structure, the peripheral edges of each spiral element lying inside the cylinder formed by the other spiral element, and removable cutting units carried along the peripheral edges of each spiral element, each unit comprising a flange of arcuate shape whose contour is generally similar to that of the peripheral edges of the spiral element, a plurality of teeth formed integrally with each flange, the cutting edges of the teeth lying generally parallel with the axis of rotation.

3. A spiral cutting apparatus including a spiral conveyor structure and a plurality of cutting units secured along the marginal edges thereof, each unit comprising a flange and a plurality of cutting teeth formed integrally with the flange the direction of movement ward spiral element.

edges lying generally parallelwith the axis of rotation of the spiral structure, one edge of each successive cutting tooth, and the adjacent edge of the next succeeding cutting tooth, lying generally in the same plane of rotation of the spiral structure, whereby a substantially complete cylinder is cut on each rotation of the spiral structure.

4. A trench-digging apparatus adapted to be mounted on a power-driven vehicle, said apparatus comprising a frame structure carried by the vehicle, a plurality of substantially parallel, V

shafts journalled in said frame structure, one to the rear of the other, spiral conveyor elements carried by each shaft, means for simultaneously rotating the spiral elements, and cutting teeth carried adjacent the peripheries of each of said spiral conveyor elements, the cutting teeth of each spiral element lying inside the cylinder formed by the cutting teeth of the otherspiral element, the cutting teeth of the rear spiral element removing the accumulated material from the forward spiral element.

5. A trench-digging apparatus adapted to be mounted on a power-driven vehicle, said apparatus comprising a frame structure carriedby the vehicle, a plurality of substantially parallel shafts journalled in said frame structure, one

to the rear of the other, right and left hand spiral conveyor elements carried by the respective shafts, means for rotating the spiral elements in opposite directions, and cutting teeth carried adjacent the peripheries of each of said spiral conveyor elements, the cutting teeth of each spiral element lying'inside the cylinder formed by the cutting teeth of the other spiral element, the cutting teeth of the rear spiral element removing the accumulated material from the for- JOHN. H. MACKINNON.

REFERENCES CITED The following references are of record in the file of this patent:

. UNITED STATES PATENTS Sweden Jan. 3, 1916 

